keyval: Document issues with 'any' and alternate types
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <1490014548-15083-5-git-send-email-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
diff --git a/util/keyval.c b/util/keyval.c
index 46cd540..93d5db6 100644
--- a/util/keyval.c
+++ b/util/keyval.c
@@ -61,6 +61,16 @@
* "key absent" already means "optional object/array absent", which
* isn't the same as "empty object/array present".
*
+ * Design flaw: scalar values can only be strings; there is no way to
+ * denote numbers, true, false or null. The special QObject input
+ * visitor returned by qobject_input_visitor_new_keyval() mostly hides
+ * this by automatically converting strings to the type the visitor
+ * expects. Breaks down for alternate types and type 'any', where the
+ * visitor's expectation isn't clear. Code visiting such types needs
+ * to do the conversion itself, but only when using this keyval
+ * visitor. Awkward. Alternate types without a string member don't
+ * work at all.
+ *
* Additional syntax for use with an implied key:
*
* key-vals-ik = val-no-key [ ',' key-vals ]
